Mounting host directories into VMs does not work for per-user restricted projects #1682
Description
When using host directory mounts with VMs in per-user restricted projects the mount point is not visible inside the VM:
$ incus create images:debian/bookworm/cloud testvm --vm
Creating testvm
$ incus config device add testvm shared disk source=/home/debian/Desktop/ path=/mnt/shared
Device shared added to testvm
$ incus start testvm
$ ps -ef | grep '[v]irtiofsd'
nobody 509871 207232 0 17:21 ? 00:00:00 /usr/bin/virtiofsd --fd=3 --cache=never -o source=/var/lib/incus/devices/user-1000_testvm/disk.shared.mnt-shared
nobody 509873 509871 0 17:21 ? 00:00:00 /usr/bin/virtiofsd --fd=3 --cache=never -o source=/var/lib/incus/devices/user-1000_testvm/disk.shared.mnt-shared
$ incus shell testvm
root@testvm:~# grep shared /proc/mounts
root@testvm:~# dmesg | grep incus_shared
[ 3.252654] virtio-fs: tag <incus_shared> not found
[ 3.259809] 9pnet_virtio: no channels available for device incus_shared
When repeating the above in the default project it does work. I am using incus 6.0.3 on Debian bookworm.
See also https://discuss.linuxcontainers.org/t/unable-to-mount-host-directory-into-vm/23001